Crushers are used to crush large particles (e.g., rocks) into smaller particles. One particular type of crusher is known as a gyratory crusher, which for the purposes of this invention also incorporates cone crushers. Typically such a crusher includes a frame supporting a head and a mantle secured to the head. A bowl and bowl liner are supported by the frame so that an annular space is formed between the bowl liner and the mantle. In operation, large particles are fed into the annular space between the bowl liner and the mantle. The head, and the mantle mounted on the head, gyrate about an axis, causing the annular space to vary. As the distance between the mantle and the bowl liner varies, the large particles are compressed between the mantle and the bowl liner. The particles are crushed and reduced to the desired product size, and then dropped down from between the mantle and the bowl liner.
In such crushers there is an eccentric assembly with an oblique (inclined and offset) inner bore. In the bore is fitted a main shaft separated from the eccentric by an eccentric bushing. The main shaft is, like the eccentric, also positioned at a slight angle to the vertical. A crushing head is attached to the main shaft. When the eccentric shaft is rotated, the main shaft together with the head moves in a pendulum motion and rotates due to the frictional forces between the bushing and the shaft. The main shaft typically rotates at about 10% of the rate that the eccentric rotates. In addition, the main shaft of a rotates at about 10% of the rate that the eccentric rotates. In addition, the main shaft of a gyratory crusher is usually adjustable by a hydraulic system whereby the main shaft is adaptable to be moved vertically relative to the crusher frame.
Information on the position and the rpm of the main shaft can be used as a diagnostic tool to determine the condition of the bushings and the inner eccentric bearings of the crusher and to also diagnose other irregularities in the crusher. Analyzing the movement of the main shaft—both its rpm and its vertical movement—can serve as a means of diagnosing the condition of a gyratory or cone crusher. As more data is available relating to the movement of the main shaft, a more accurate diagnosis can be made of the operating condition of the crusher. For example, measuring the rotational speed of the main shaft, and determining changes from a baseline rpm speed when the machine is under load and not under load, will provide information on the condition of the machine's eccentric bushing. Likewise, recording a change in the position of the main shaft noted as a change in the height of the main shaft from a normal operating setting serves to record any drift of the support cylinder due to normal leakage of hydraulic oil as well as determining if a tramp event occurred, and can further determine if adjustments must be made to the height of the main shaft to maintain correct product sizes. Additionally, data relating to the direction of rotation i.e., either clockwise or counterclockwise, and any change in the tilt of the main shaft from its normal position can also be used to interpret rotational speed data and relate it to the overall crusher condition.
A method of measuring axial height of the main shaft of a gyratory crusher utilizing a sensor located at the bottom of the main shaft by measuring the location of the hydraulic support piston is known in the art. The sensor does not measure any other aspect of the movement of the main shaft. Because of its location, it is difficult and potentially dangerous to gain access to such sensors for maintenance or other purposes.
It is an object of this invention to have a diagnostic detection apparatus and method of monitoring a number of variables relating to the movement of the crusher's main shaft. It is a further object to utilize a single emitting transducer, a single target, and a single set of data to analyze all pertinent aspects relating to the movement of the crusher's main shaft.
The figures are not necessarily drawn to scale.